Method for cyclically preparing titanium sponge and coproducing potassium cryolite using potassium fluotitanate as intermediate material

ABSTRACT

A method for cyclically preparing titanium sponge and coproducing potassium cryolite using potassium fluotitanate as an intermediate material, which includes the following steps: A) adding hydrofluoric acid to titaniferous iron concentrate to enable a reaction to form fluotitanic acid; B) adding potassium sulphate to the fluotitanic acid to enable a reaction to form the potassium fluotitanate; C) putting the potassium fluotitanate into a reactor, adding aluminium to react with the potassium fluotitanate to form the titanium sponge and potassium cryolite; D) extracting the potassium cryolite and sending it to a rotary reaction kettle together with concentrated sulphuric acid to enable a reaction to form hydrogen fluoride gas and potassium sulphate, aluminium potassium sulphate; collecting the hydrogen fluoride gas and dissolving it into water to obtain a hydrofluoric acid aqueous solution; E) recycling the obtained hydrofluoric acid aqueous solution to Step A to leach the titaniferous iron concentrate.

TECHNICAL FIELD OF THE INVENTION

The disclosure relates to a method for preparing titanium sponge, and inparticular to a method for cyclically preparing titanium sponge andcoproducing potassium cryolite using potassium fluotitanate asintermediate material.

BACKGROUND OF THE INVENTION

Titaniferous iron concentrate is the main mineral raw material forextracting titanium. The existing titanium sponge preparation methodtakes the titaniferous iron concentrate as an initial material, obtainsa rich-titanium material through a reducing smelting process, achlorinated melting process, a pre-reduction hydrochloric acid leachingprocess or a pre-reduction sulphuric acid leaching process, takestitanium tetrachloride which is formed by reacting the rich-titaniummaterial with coke and chlorine gas at a high temperature of about 1000DEG C. as an intermediate material, and then prepares the titaniumsponge through a magnesium thermic reduction process (Kroll process) ora sodium thermic reduction process (Hunter process), wherein thereducing smelting process needs a high temperature of between 1700 and1800 DEG C. and obtains the rich-titanium material after using coke toperform reduction; the chlorinated melting process needs a hightemperature of about 1000 DEG C. and obtains the rich-titanium materialafter using coke and chlorine gas to perform reaction; the pre-reductionhydrochloric acid leaching process needs to be carried out at a hightemperature of about 1200 DEG C., and uses hydrochloric acid to performleaching after using coke to perform pre-reduction, and then heats anddehydrates the titanic acid formed to obtain the rich-titanium material;the pre-reduction sulphuric acid leaching process needs to be carriedout at a high temperature of about 1200 DEG C., and uses sulphuric acidto perform leaching after using coke to perform pre-reduction, and thenheats and dehydrates the titanic acid formed to obtain the rich-titaniummaterial. The titanium tetrachloride will generate correspondingcoproduct chlorate while preparing titanium sponge through the magnesiumthermic reduction process (Kroll process) or the sodium thermicreduction process (Hunter process), and it is necessary to adopt amelting electrolytic method to separate and recycle the metal andchlorine gas.

Therefore, the conventional art for preparing titanium sponge usingtitanium tetrachloride as an intermediate material has disadvantagessuch as complex processes, demanding reaction conditions, high equipmentinvestment requirements, relatively long production cycle, highproduction cost and non-environment friendly use of chlorine gas.

SUMMARY OF THE INVENTION

In order to solve the problem existing in the conventional art, theinventor has done a great deal of research in the selection ofintermediate material and the circular process of coproduct andunexpectedly finds that the method for producing titanium sponge usingpotassium fluotitanate as an intermediate material has a simple process,recycles the coproduct, lowers the production cost and reduces thepollution to environment.

The disclosure provides a method for cyclically preparing titaniumsponge and coproducing potassium cryolite using potassium fluotitanateas an intermediate material, which includes the following steps:

A) adding hydrofluoric acid to titaniferous iron concentrate to enable areaction at a temperature of between 100 and 200 DEG C. to formfluotitanic acid, wherein the main reaction formula involved is:6HF+TiO₂═H₂TiF₆+2H₂O.

B) adding an aqueous solution of potassium sulphate to the fluotitanicacid to enable a reaction to form a potassium fluotitanate precipitate,centrifuging and rinsing the potassium fluotitanate precipitate toobtain the intermediate material potassium fluotitanate, wherein themain reaction formula involved is: H₂TiF₆+K₂SO₄═K₂TiF₆↓+H₂SO₄;

C) putting dried potassium fluotitanate into a reactor, injecting aninert gas to the reactor after vacuumizing, heating the reactor to atemperature of between 780 and 850 DEG C., adding aluminium in thereactor and stirring quickly to enable a reaction for 4 to 6 hours toform the titanium sponge and potassium cryolite; or, putting thealuminium into the reactor, injecting an inert gas to the reactor aftervacuumizing, heating the reactor to the temperature of between 780 and850 DEG C., adding dried potassium fluotitanate in the reactor andstirring quickly to enable a reaction for 4 to 6 hours to form thetitanium sponge and potassium cryolite; after being kept stand, thesupernatant liquid is potassium cryolite and the lower layer of titaniumsponge can be removed of surface residual through acid leaching ordistillation, wherein the main reaction formula involved is:

${{{\frac{3}{4}K_{2}{TiF}_{6}} + {Al}} = {{\frac{3}{4}{Ti}} + {AlF}_{6}}},{{\frac{3}{2}{KF}};}$

D) extracting molten liquid potassium cryolite; after the molten liquidpotassium cryolite is cooled, crushing and sending it to a rotaryreaction kettle quantificationally together with concentrated sulphuricacid to enable a reaction at a temperature of between 400 and 500 DEG C.to form hydrogen fluoride gas and the solid mixture of potassiumsulphate and aluminium potassium sulphate; collecting the hydrogenfluoride gas and dissolving it into water to obtain a hydrofluoric acidaqueous solution; reacting the solid mixture of potassium sulphate andaluminium potassium sulphate with an aqueous solution of potassiumhydroxide after crushing the solid mixture of potassium sulphate andaluminium potassium sulphate, and obtaining the aqueous solution ofpotassium sulphate after separating out the solid aluminium hydroxide,wherein the main reaction formula involved is:

${AlF}_{6},{{{\frac{3}{2}{KF}} + {\frac{9}{4}H_{2}{SO}_{4}}} = {{\frac{9}{2}\left. {HF}\uparrow{+ \frac{1}{4}} \right.K_{2}{SO}_{4}} + {{KAl}\left( {SO}_{4} \right)}_{2}}},{{{{K_{2}{SO}_{4}} + {{KAl}\left( {SO}_{4} \right)}_{2} + {3{KOH}}} = {{3K_{2}{SO}_{4}} + \left. {{Al}({OH})}_{6}\downarrow \right.}};}$

E) recycling the obtained hydrofluoric acid aqueous solution and theaqueous solution of potassium sulphate to the front end to leach thetitaniferous iron concentrate, so as to achieve the purpose ofcyclically preparing the intermediate material potassium fluotitanate.

With the technical scheme above, potassium fluotitanate is used toreplace titanium tetrachloride as the intermediate material forpreparing titanium sponge, thus, the process is simple, the reactioncondition is relatively mild, the production flow is short, the obtainedcoproduct potassium cryolite can realize the cyclic regeneration ofpotassium fluotitanate only needing common chemical materials such asindustrial concentrated sulphuric acid and potassium hydroxide, it isnot necessary to use chlorine gas and perform melting electrolysis, theproduction cost is lowered and the pollution to environment is reduced.

The technical scheme adopted above overcomes the disadvantages in theconventional such as complex processes, high equipment investmentrequirements, high production cost, relatively long production cycle andbeing easy to result in environmental pollution.

As a further improvement of the disclosure, in Step C, the aluminium ismolten aluminium which is added in the reactor in a dripping way, or thealuminium is added in the reactor first and then dried potassiumfluotitanate is batch-fed in the reactor after the aluminium is molten,wherein the completeness of this reaction can be greater than or equalto 95%.

As a further improvement of the disclosure, in Step C, the inert gas isargon.

Compared with the conventional art, the disclosure achieves advantagesas follows: using potassium fluotitanate as an intermediate material,the preparation method has a simple process and a short productioncycle, and improves production efficiency; the coproduct is potassiumcryolite, which has a high commercial value and a good applicationprospect and can be used as a source of the intermediate materialpotassium fluotitanate; thus, fully cyclic regeneration of resource isrealized, melting electrolysis is avoided, the comprehensive cost ofproduction of titanium sponge is lowered and the pollution toenvironment is reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a process route chart of preparing titanium spongeaccording to the disclosure;

FIG. 2 shows an existing popular process route chart of preparingtitanium sponge; and

FIG. 3 shows a process flowchart of preparing titanium sponge accordingto the disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The disclosure is described below in further detail through specificembodiments.

Embodiment 1

Putting 1 ton of titaniferous iron concentrate powder into a reactionkettle; adding 1.5 tons of 30% (volume percent) hydrofluoric acid in thereaction kettle to fully react with the titaniferous iron concentratepowder at a temperature of 120 DEG C. to form fluotitanic acid; afterthe fluotitanic acid is cooled, adding 4 tons of 10% (mass percent)potassium sulphate solution to the fluotitanic acid to enable a fullreaction to form a potassium fluotitanate precipitate; centrifuging,rinsing and drying the potassium fluotitanate precipitate to obtainpotassium fluotitanate; weighing and putting the potassium fluotitanateinto another reactor; injecting an inert gas to the reactor forprotection after vacuumizing, heating the reactor to a temperature of800 DEG C.; dripping molten aluminium into the reactor slowly inaccordance with a reaction ratio, stirring quickly and enabling areaction for 5 hours to form titanium sponge and potassium cryolite;opening the cover of the reactor, pumping the superstratum potassiumcryolite through a siphon-pump and distilling the lower layer oftitanium sponge at a temperature of 1000 DEG C. under vacuum to obtainpurified titanium sponge; crushing and weighing the potassium cryoliteafter it is cooled and adding concentrated sulphuric acid to thepotassium cryolite in accordance with a reaction ratio; reacting thepotassium cryolite with the concentrated sulphuric acid at a temperatureof between 400 and 500 DEG C.; condensing and collecting the formedhydrogen fluoride gas and dissolving it into water to obtainhydrofluoric acid; dissolving the solid mixture obtained by reacting thepotassium cryolite with the concentrated sulphuric acid into water aftercrushing the solid mixture, and adding a calculated mount of 10% (masspercent) potassium hydroxide aqueous solution; performing filtering toremove aluminium hydroxide and obtain an aqueous solution of potassiumsulphate.

Embodiment 2

Putting 1 ton of titaniferous iron concentrate powder into a reactionkettle; adding 1.5 tons of 30% (volume percent) hydrofluoric acid in thereaction kettle to fully react with the titaniferous iron concentratepowder at a temperature of 120 DEG C. to form fluotitanic acid; afterthe fluotitanic acid is cooled, adding 4 tons of 10% (mass percent)potassium sulphate solution to the fluotitanic acid to enable a fullreaction to form a potassium fluotitanate precipitate; centrifuging,rinsing and drying the potassium fluotitanate precipitate to obtainpotassium fluotitanate; weighing the potassium fluotitanate; weighingaluminium in accordance with a reaction ratio and putting the aluminiuminto another reactor; injecting an inert gas to the reactor forprotection after vacuumizing, then heating the reactor to a temperatureof 800 DEG C.; adding dried potassium fluotitanate in the reactorslowly, stirring quickly and enabling a reaction for 5 hours to formtitanium sponge and potassium cryolite; opening the cover of thereactor, pumping the superstratum potassium cryolite through asiphon-pump and distilling the lower layer of titanium sponge at atemperature of 1000 DEG C. under vacuum to obtain purified titaniumsponge; crushing and weighing the potassium cryolite after it is cooledand adding concentrated sulphuric acid to the potassium cryolite inaccordance with a reaction ratio; reacting the potassium cryolite withthe concentrated sulphuric acid at a temperature of between 400 and 500DEG C.; condensing and collecting the formed hydrogen fluoride gas anddissolving it into water to obtain hydrofluoric acid; dissolving thesolid mixture obtained by reacting the potassium cryolite with theconcentrated sulphuric acid into water after crushing the solid mixture,and adding a calculated mount of 10% (mass percent) potassium hydroxideaqueous solution; performing filtering to remove aluminium hydroxide andobtain an aqueous solution of potassium sulphate.

The above are the further detailed description of the disclosure made inconjunction with specific preferred embodiments; it can not beconsidered that the specific embodiment of the disclosure is onlylimited to the description above. For the common technicians in thetechnical field of the disclosure, umpty simple deductions orsubstitutes can be made without departing from the concept of thedisclosure and they are deemed to be included within the scope ofprotection of the disclosure.

What is claimed is:
 1. A method for cyclically preparing titanium spongeand coproducing potassium cryolite using potassium fluotitanate as anintermediate material, which includes the following steps: A) addinghydrofluoric acid to titaniferous iron concentrate to enable a reactionat a temperature of between 100 and 200 DEG C. to form fluotitanic acid;B) adding a potassium sulphate solution to the fluotitanic acid toenable a reaction to form a potassium fluotitanate precipitate,centrifuging and rinsing the potassium fluotitanate precipitate toobtain the intermediate material potassium fluotitanate; C) puttingdried potassium fluotitanate into a reactor, injecting an inert gas tothe reactor after vacuumizing, heating the reactor to a temperature ofbetween 780 and 850 DEG C., adding aluminium in the reactor and stirringquickly to enable a reaction for 4 to 6 hours to form the titaniumsponge and potassium cryolite; or, putting the aluminium into thereactor, injecting an inert gas to the reactor after vacuumizing,heating the reactor to the temperature of between 780 and 850 DEG C.,adding dried potassium fluotitanate in the reactor and stirring quicklyto enable a reaction for 4 to 6 hours to form the titanium sponge andpotassium cryolite; D) extracting molten liquid potassium cryolite;after the molten liquid potassium cryolite is cooled, crushing andsending it to a rotary reaction kettle quantificationally together withconcentrated sulphuric acid to enable a reaction at a temperature ofbetween 400 and 500 DEG C. to form hydrogen fluoride gas and the solidmixture of potassium sulphate and aluminium potassium sulphate;collecting the hydrogen fluoride gas and dissolving it into water toobtain a hydrofluoric acid aqueous solution; reacting the solid mixtureof potassium sulphate and aluminium potassium sulphate with an aqueoussolution of potassium hydroxide after crushing the solid mixture ofpotassium sulphate and aluminium potassium sulphate, and obtaining theaqueous solution of potassium sulphate after separating out the solidaluminium hydroxide; and E) recycling the obtained hydrofluoric acidaqueous solution and the aqueous solution of potassium sulphate to thefront end to leach the titaniferous iron concentrate, so as to achievethe purpose of cyclically preparing the intermediate material potassiumfluotitanate.
 2. The method for cyclically preparing titanium sponge andcoproducing potassium cryolite using potassium fluotitanate as anintermediate material according to claim 1, wherein in Step C, thealuminium is molten aluminium which is added in the reactor in adripping way or the dried and flowable potassium fluotitanate is addedin the reactor in a measurable flowing way.
 3. The method for cyclicallypreparing titanium sponge and coproducing potassium cryolite usingpotassium fluotitanate as an intermediate material according to claim 1,wherein in Step C, the inert gas is argon.